Method



May 8, l923- y `1,454,154 K. F. COOPER METHOD OF AND APPARATUS FORFUMIGATING 'Filed Jan. 2S. 1921 Patented May 8, 1923.

KENNETH F. COOPER, OF GREAT NECK, NEW YORK, ASSIGNOR T0 AMERICAN CYAN-AMID COMPANY, OF NEW YORK,

N. Y., A CORPORATION 0F MAINE.

METHOD OF AND APPARATUS FOR FUMIGATING.

Application filed. January' 25, 1921.

To ZZ whom it may concern Be it known that I, KENNETH F. CoornI-z, acitizen of the United States, residing at Great Neck,in the county ofNassau and State of New York, have invented certain new and usefulImprovements in Methods of and Apparatus for Fumigating; and I do herebyde- Clare the following to be a full, clear, and exact description ofthe invention, such as willenable others skilled in the art to which :itappertains to make and use theI same.

This invention relates to a process for the application of volatileliquid fumigants such, for example, as liquid hydrocyanic acid, and toan apparatus for carrying out such application, and has lfor its objectto provide a process and apparatus which will be more effective and moreeconomical in use than those heretofore proposed.

W'ith these and other objects iu viewfhis invention consists in thenovel steps and combinations of steps constituting the process, and inthe novel combinations of parts constituting the apparatus, all as willbe more fully hereinafter disclosed, and particularly pointed out in theclaims.

In order that my invention may bc more clearly understood, it is said:

`In fumigating with liquid hydrocyanic acid or similar volatile fumigantfor the extermination of insects, rodents and various other pests, thefollowing is a description of one method of procedure, as at presentcarried out.

The volume of the space to be fumigated is first accurately determined,and from this volume the actual and effective dosage of the liquidrequired is arrived at by referring to a. previously prepared chart. Theenclosure is then made as nearly gas-tight as possible, as, forinstance, in the case of a room the windows being tightly closed andlatched, and all doors and ventilators closed and sealed. The dosage ofthe liquid is then carefully measured and atomized into the enclosurethrough any convenient opening. In this atomized state the fumigantevaporates with greater or less velocity` depending on the temperature,degree of atomization and other similar factors.

The opening is then closed and sealed as quickly as possible, and theroom is allowed to remain in this condition for a sufficient time untilkilling has been effected, this time Serial No. 439,784.

depending upon the size and shape of the room, and the temperature atwhich the fumiffation is carried out.

or instance, in a very large room with a great many irregularities, suchas nooks and alcoves, and when the temperature is comparatively low, thetime required for effective fumigation is longer than it would be undermore favorable conditions. In the case of a theatre where the outline ofthe space of the room is very irregular, and in the holds of vesselswhere this same condition applies, the time required for effectivefumigation often takes several hours. It must also be borne in mind thatin order to get an effective killing of all the pests it is absolutelynecessary to get a uniform distribution of the gas throughout the wholespace. In the case, for instance, one is fumigating for the purpose ofkilling flies, the gas must permeate in suflicient concentration to theceilings, walls and cracks where these ies are found, while in the caseof rats, the gas must enter into their holes and hidino, places in therequired concentration.

Vith the equipment heretofore proposed it is necessary to depend forthis distribution on the ratel of diffusion of the gas of the particularfumigant employed, -but since the temperature at which such work isusually carried out may be below the boiling point of the fumigantsemployed, and further, due to the high heat absorption incident tovaporization of the fumigants, and the consequent cooling effect on thevapor, the subset uent diffusion may be very materially sowed down.Regardless of how careful one is in stopping' up the leaks in such anenclosure, there is always a very large percentage of leakage of thegaseous material before complete diffusion has been effected. Anexcessive dosage may be therefore required so as to procure the desiredfinal effective concentration of the poisonous gas in places remote fromthe point of application, and such an overdose, of course, necessitatesa material extra cost of valuable fumigating material.

Another serious disadvantage of this method of fumigating is the longtime required to obtain the uniform effective concentration. This is avery important factor in the fumigation of busy office buildings andfactories which are in constant use, and

.vhere vacating necessitates great inconvenience and expense. It istherefore desirable in vvork of this sort that the tumigant beintroduced in a gaseous form, under such conditions as o facilitaterapid mixing and diffusion so that a uniform effective concentration ofthe killing gas may be had in the shortest possible time, and I am heredisclosing a means of vaccomplishing` the desired results in a uniqueand effective manner.

Liquid hydrocyanic acid, because of its very poisonous nature, has notbeen quantitatively studied by the physicist. Its boiling point isapproximately 80@ l?. While its latent heat of evaporation is relativelyhigh, but not quite as much as that of Water. It freezes to a solid atapproximately OO F. and at ordinary summer temperature when poured on aHat surface, it evaporatesso rapidly that it solidifies. due to thecooling incident to the rapid evaporation.

It has been found not to be a satisfactory method of application to pourout the liquid on a Vfloor and permit it to evaporate, because thematerial freezes and then slowly gasifies which greatly prolonge thetime required for thorough fumigation. IW hen atomized it rapidlyevaporates, but the vapor isso cold that it tends to hang around thelower parts of the space being fumigated and diffusion is consequentlyslow.

In my improved apparatus I take into account these physical propertiesof liquid hydrocyanic acid and eliminate the disadvantage of using thematerial as an ordinary fumigant by gasification before application. Inthe first place, realizing that fumigation must be carried on rapidly inorder to utilize equipment and labor most effectively, it is necessarythat any scheme ot" evaporation be such that considerable quantities ofthe liquid can be changed to gas in a very short space of time. Inviewof the very considerable heat absorption during evaporation, I proposeto perforn. this function by providing a large storage or reservoir ofheat,y which storage is continuously supplied directly through theburning ot fuel, or by the application of steam, or otherwise, and todraw upon this heat storage as required for the rapid evaporation orsuccessive dosages of' liquid hydrocyanic acid.

One example vof such storage would be a hot Water system or a steamboiler in which I continuously supply heat by combustion at a limited'orreasonable rate, and draw ofi" this heat as needed for performing myevaporation of the liquid hydrocyanic acid. I

fuel7 at some distance from the containers and gasifying equipment,which is a decided advantage when one considers the inflammability ofthe hydrocyanic acid. It also permits taking advantage of using acomparatively low-temperature source of heat for the vaporization, suchas low pressure steam or even hot water,

I can also accomplish the same result by using as my evaporator, a metal`container of heavy construction, which in itself can store up largequantities of heat and deliver the same up to the liquid incomparatively short time. But, on the other hand, hydrocyanic acid gasheated in contact with metal is decomposed rather readily, and it is,therefore, of decided advantage to carry on its evaporation through suchmedium as hot Water 'or steam to prevent overheating. Direct heatingover a flame in a thin-Walled evaporator likewise possesses thedisadvantage of having to use a flame of considerable intensity in orderto rapidly evaporate the liquid hydrocyanic acid, and it would benecessary to control this flame very sharply so as to avoid undueheating of such apparatus between successive doses. This of necessityWould complicate the apparatus and introduce an element of dangerbecause of the unskilled character of the labor usually doing the Work.On theother hand, vthe indirect system of evaporation which Ifhaveproposed eliminates these difficulties by permitting the source of heatto act with greater uniformity and at the same time permitting the readyWithdrawal of heat from the storage vessel as needed in the vaporizer.

In the application of gaseous hydrocyanic acid, it is frequentlynecessary to carry it through comparatively long'pipe lines or hoselines to reach the point of fumigation. Since the vapor taken oil" ofthe boiling liquid is saturated and Will condense with any drop intemperature, and since considerable fumigation isv doneat temperaturesbelow the boiling point of this liquid, it is necessary itlE accuratedosages are to be secured, to prevent such a condensation in the pipelines used to convey the gas. lVliile superheating of the vapor Willeliminate this condensation to a degree, and I use vthis principle forcertain cases of fumigation, I have found that under certain conditionssuch superheat is not always suflicient to avoid condensation. In thesecases I find it of material advantage toprevent the condensationA of thehydrocyanio acid to the liquid form, by introducing into said acid airor 'other inert gas along With the issuing stream of vapor. leaving thevaporizer.

Referring now to Vthe accompanying drawings, forming a part of thisspecication in which like numerals designate like parts in all theviews:

Figure l is a. diagrammatic transverse lll) lill

sectional elevational view of one form of apparatus suitable forcarrying out the present method; and

Figure 2 is a detail sectional view of the heating chamber.

1 indicates a suitable frame, or bed, mounted upon the wheels 2, andcarrying upon it in any suitable manner the tank 3, provided with thefilling plug 4. The said tank 3 may be connected at or near itslowermost portion as by a pipe 5, provided with a valve 6, to the upperportion of the receiving tube or chamber 7. The said receiver 7 ispreferably closed at its upper end and provided with a stuffing box 8,through which passes the hollow tube or pipe 9, which is connected atits upper end by means of the hollow handle 10 with the tube or pipe 11.The said pipe 11 passes through the stuffing box 12 into the tubularmember 13, which permits said pipe to move up and down while maintaining.a tight joint with the stuffing box 12. The lower end of the tube 13 isconnected as by the pipe 14, provided with check valve 14, to

the mixing chamber 15, as will be clear from the drawings.

Also mounted upon the frame 1 is a pump 16, provided with a piston 17adapted to be actuated by the piston rod 1S and handle 19, and the saidpump is connected as by the piping 2O with the upper end of the receiver7, substantially as shown.

The apparatus as thus far disclosed, with the exception of the frame 1,wheels 2, and mixing chamber 15, is or may be substantially the same asdisclosed in my copending application filed December 29, 1920, Ser. No.433,876, and entitled Fumigating apparatus.

A second pump is mounted upon the frame 1, and provided with a piston 26adapted to be actuated by means of the piston rod 27 and handle 28, andthe said last mentioned pump is joined as by the piping E29 to themixing chamber 15` see Figure 1. The pipes 20 and 29 may, if desired, beprovided with suitable check valves 20"* and 29 to permit the flow offluid away from the pumps 16 and 25 re speetively, but preventing areturn thereto.

rlhe mixing chamber 15 is connected by a pipe 30 to tlie heatingreceptacle 31, which comprises a shell 32, provided with a pair ofheaders or partitions 33 and 34, forming a plurality of chambers 35, 36and 37. The pipe 30 passes through the shell 32, and through the chamber35. and communicates with the chamber 37, while communication betweenthe chambers and 36, which are adapted to contain water, oil, or otherheat storing medium, is provided by means of a plurality of tubes orpipes 38 passing through and secured in the headers or partitions and34, as will be clear from Figure 2. A discharge pipe or hose 39 leadsfrom the chamber 37 to any suitable form of atomizing nozzle 40, hereshown as introduced through the wall or partition 41 into the enclosure42 to be fumigated.

The valve 6 may be controlled by means of the rod 43 provided with theknob or handle 44, while 45 designates any suitable form of indicatorsuoli as is usually employed with apparatus of this general type, whichindicator is preferably secured to the receiver' 7 substantially asshown.

Any suitable means may be provided for supplying heat to the receptacle31, such, for example, as the liquid fuel burner 46, carried below thesaid receptacle 31 by au extension 47 of the frame 1.

The mode of using the apparatus above described in carrying out thepresent method will be clear from the foregoing, but may be brieflysummarized as follows:

The tank or container 3 is first filled b v removing the plug 4, fillingthe container by any approved method, and then again screwing plug 4back into place. The handle 1() connected to tubes 9 and 11 is thenadjusted to any desired position, depending on the dosage required andthe valve 6 is opened, whereupon liquid from container 3 will f'low intothe receiver 7, and the entrapped air previously contained in receiver 7will be forced out through the tubes 9, 11, 13. 14 and 39. After thereceiver 7 is completely filled with liquid, the valve 6 is again closedby releasing the handle 44, and both the air pumps 16 and 25 are broughtinto operation by means of the handles 19 and 28. The pressure suppliedby the air pump 16 is communicated to the liquid contained in thereceiver 7 through the pipe or tube 20, causing the liquid to passthrough the tubes 9, 1() and 11 into the tube 13, then through the pipe14 to the mixer' 15, where it is combined with the compressed air fromthe pump Q5, entering through pipe 29. The mixture of air and liquidthen passes by way of the pipe 30 to and through the space 37 aroundtubes 38, which space is heated by means of the heater' 46 through thestorage medium of hot water or other fluid contained in the chambers 35and 36, and pipes 38. The liquid fumigant is here vaporized and themixture of hot air andvapor passes through the pipe or hose 39 andnozzle 40 l into the enclosure 42.

In practice the tube 9 may be adjusted up and down through the stuffingbox 8, whereupon the indicator carried by said tube, not lettered, willindicate on the scale member 45 the'position of the lower end of thetube in the chamber 7. Knowing the position of this said lower end ofthe tube 9, the operator will `know with accuracy the amount of liquidwhich will be forced out of the chamber 7 when air through the pipe 20is forced Lll) into the top of said chamber. rl"his said predeterminedamo-unt ot' liquid, When forced out of chamber 7, enters the pipe ll andthe tube 13, and is forced from there into the mixing chamber l5. Thetube I3 is made larger than the tube 1l so that the latter may readilymove up and down therein when the tube 9 is adjusted for measuring thefluid in the manner above disclosed. In the chamber the liquid `issubjected to the pressure of air from the pipe 29 and is forced throughthe pipe 30 and into the spaces 37 betiveen the pipes 38, see Fig. 2,which causes saidair to mix With said liquid. Es pecially is this thecase when the said chambers 87 are heated from the tubes 38 andtherefore, when the umigant is forced out through the pipe 39 it is Wellmixed with air.

.It is also evident from the method ot operation previously describedabove that these parts may be somewhat rearranged. vlli`or instance, themeasuring device described is but one means of obtaining the desiredresult, and I am aware that I could employ an y of several methods to dothis measuring. It is further evident, in this particular ior instance,that I might use but one air compressor and by suitable manipulationaccomplish the same purpose as the tivo compressors 16 and 25 shown.

ItWill be seen from 'the above disclosure that my process and apparatusis capable oi meeting the peculiar and unusual demands ol the fumigatingindustry for the use ot a volatile liquid tumigant. I have provided thenecessary measuring equipment to ,insure accurate dosagev of the liquidand in a sim ple and easy manner, I discharge this dosage into avaporizer which is so constructed that evaporation takes place veryrapidly due to a considerable heat storage intimately connected with thevaporizer. This enables me to take the large dosages usually used inthis work and instantly evaporate them to gas, and, While the apparatusis being moved to a. new position, to generate and store heat tor use inthe next application. By the present construction and process I storethis heat at moderate temperatures and so do not subject the 'umigantto'extremes ot temperature with the accompanying danger ofdecomposition. The apparatus further is capable or' superheating thegaseous fumigant, but since only a limited amount of superheat can be`safely carried in this vapor, I, at the same time, can reduce the dewpoint so asl to avoid condensation of the vapor in the tube such as 39carrying the same from the vaporizer to the point of application. Myapparatus is safe, inasmuch as I may have my source of heat entirelydistinct and separate from the vaporizer and should leakage of thevaporizer occur, the liquid iumigantor its vapor are not likely to comeinto contact with an open flame and cause tire or explosion.

I gain considerable rapidity of action by this process and apparatus,which is a very important factor, as the Cost of labor constitutes alarge percentage of the total cost oit' tumigation. This apparatus willfurther deliver very exact dosages, as it is completely flushed out ateach discharge with an excess of Warm air'. From a small quantity ofvapor used, by mixing with a considerable portion ofair in the apparatusitself, I obtain in consequence a very much quicker and thorough mixingof the tumigant in the space to be fumigated and consequently obtain amuchquicker and eilective applicaVv tion than Where dependent upon thenatural diffusion of cold vapors. As a consequence the spaces to befumigated are out of service tor a minimum length of time.

The apparatus is comparatively cheap and simple to construct, and easilytransported, which in certain cases is a decided advantage inasmuch asin the umigation oit' fruit or other trees, or plants, it must behandled etten over loosely cultivated. soil.

It is obvious that those ski led in the art may vary the details oiconstruction and arrangement of parts constituting the apparatus, asWell as the steps constituting the process, Without departing from thespirit or' the invention, and therefore I do not Wish to be limited tothe above disclosure except as may be required by the claims.

lihat I claim is:

l. The process of applying a volatile liquid fumigant which consists inmeasuring a predetermined quantity of said itumigant in its liquid formisubjecting said measured liquid tumigant to pressure; admiXing saidmeasured fumigant With an inert gas 'under pressure g' subjecting themixture oii gas and Vfumigant to heat in excess of that required forvolatilization; and introducing the heated vaporized fumigant into thespace to be fumigated, substantially as described.

The process of applying a volatile liquid fumigant which consists inmeasuring said liquid; mixing air with the measured fumigant; subjectingthe mixture thus obtained to a quantity ot heat in excess ot' thatrequired to fully vaporize said liquid; and introducing the heatedmixture oit' vapor and air into the space to be umiofated, substantially as described.

3. The process of t'umigating with a volatile liquid iiumigant whichconsists in mixing an inert gas With said umigant; providing a heatstorage reservoir; passing said mixed gas and tumigant throughsaidreservoir to vaporize and superheat the same; and introducing saidsuperheated mixed gas and vapor into the space to be tumigated,substantially as described.

si.. The process ot 'umigating with a vola tile liquid fumigant whichconsists in measuring said fumigant; mixing said umigant with air;supplying an additional quantity of heat to the mixture to vaporize andsuperheat the same; and introducing, the superheated mixture into thespace to be fumigated, substantially as described.

5. The process of fumigating` With a volatile liquid umigant whichconsists in mixing an inert gas with said liquid; providing a mediumadapted to store and transmit heat; constantly supplyingr heat to saidmedium; subjecting a predetermined quantity of said mixed gas and liquidto the action of heat thus stored to superheat the same; and introducingthe superheated mixed gas and vapors into the space to be fumigated,substantially as described.

(3. The process of fumigating With a volatile liquid umig'ant whichconsists in providing a medium adapted to store and transmit heat;constantly supplying heat to said medium; measuring1r a predeterminedquantity oi' the said fumigant; mixing air With the fumigant; subjectingthe mixture to the action oit' the heat stored in the said medium tovaporize and superheat the saine; and introducingr the superheatedmixture into the space to be fumigated, substantially as described.

7. In a fumigating apparatus the combination of a supply tank adapted tocontain a liquid fumigant; a vaporizer provided with a heat storing andtransmitting medium and a fumigant receiving chamber; means adapted tosupply heat to said medium; means adapted to deliver a predeterminedquantity of fumigant from said tank to said vaporizer; means to admixair with said fumigant before it enters said vaporizer; and means fortransferring the vaporized mixture of air and fulnigant from saidvaporizer to the space to be fumigated, substantially as described.

8. In a liquid hydrocyanic acid umigating apparatus the combination of asupply tank adapted to contain said acid; a vaporizer adapted to receiveand store a sufficient quantity of heat to completely vaporize apredetermined portion of said acid and to super-heat said vapor; mea-nsadapted to supply said heat to said vaporizer; means adapted to transfera variable predetermined quantity of said acid from said tank to saidvaporizer; means adapted to mix an inert `fas with said predeterminedquantity of acid; and means for transferring the superheated mixturefrom said vaporizer to the space to be fumigated, substantially asdescribed.

9. In a liquid. hydrocyanic acid fumigating apparatusl the combinationof an acid supply tank; a receiver associated With said tank; a. mixingchamber; means adapted to deliver a variable predetermined quantity ofacid from said receiver to. said mixing chamber; means for supplying airto said cham-` ber; a vaporizer containing a medium adapted to receiveand store a sufficient quantity of heat to completely vaporize saidpredetermined quantity of acid and to superheat the mixture of acidvapors and air; means for constantly supplying heat to said medium; andmeans for transferring said superheated mixture from said vaporizer tothe space to be fumigated, substantially as described.

In testimony whereof I aiiix my signature.

KENNETH F. COOPER.

